Typical low power fiber lasers/amplifiers use tap couplers to harvest a small percentage of the power (typically, <1%) in the fiber core. Once the coupler taps off the power, that power can be directed to an energy monitor (power meter, detector, etc). In high power systems (typically, >1 watt) and/or systems using specialty fibers, tap couplers generally do not exist, so monitoring the output power is typically done at the output of the fiber laser system.